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Old 03-10-09, 07:57 AM   #1
rumrunn6
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Derailer Woes

2 things:

1) front derailer doesn't move the chain into the smallest of 3 gears even though there is correct amount of slack in cable and the stop screw is not holding it back. I often have to switch gears in the back derailer which helps the chain move down to the smallest gear up front. I cleaned the derailer so I don't think there is any junk keeping it from moving it's full movement. is there some adjustment to the thing that holds the chain, can I bend it a little?

2) back derailer sometimes jumps and doesn't stay where I put it, meaning I put it in one gear and it jumps until it finds a place it likes, not far but not in the gear I had it.

I have index shifting on this hybrid
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Old 03-10-09, 08:06 AM   #2
Metzinger
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I'd bet alignment is the issue with both. Front cage may be bent, angled in or out, or at an unsuitable elevation to properly push the chain.

Bent derailleur hanger on the rear is a problem I've had due to crashes. A shop can align this perfectly, but I always seem to get the results I need with a crescent wrench and eyeballing.

Look up the tech manuals for your derailleurs. They're usually available in PDF somewhere.
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Old 03-10-09, 08:21 AM   #3
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the FD cage should clear the biggest chainring by about 0.5~2mm and the outer plate should be parallel to it.
sometimes you have to pivot the cage a bit to get the FD to properly derail the chain.

also double check that your cables are not rusted or gummed up.
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Old 03-10-09, 12:18 PM   #4
Gonzo Bob
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What kind of front derailer? Is it top-swing? I had a lot of difficulty with a replacement top-swing on my MTB. I had to keep it really clean and lubed or it wouldnt shift down without a little persuasion (pushing in with fingers or tapping with my toe). I got so frustrated with it that I ended up putting the old bottom-swing front derailer back on.
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